Hydraulic coupling with metallic sealing member

ABSTRACT

A hydraulic coupling is disclosed for connecting a hydraulic line to a hydraulic component such as a pump, compressor, cylinder or the like. The coupling consists of an adapter which fits into an opening in the hydraulic component. In order to form a leak-free joint between the adapter and the hydraulic component, a heat recoverable metallic sealing ring is placed between the surfaces. A heat recoverable sleeve is affixed to the hydraulic line and this sleeve mates with the adapter to form a seal. This seal results from the contact of a mating surface on the adapter and a corresponding mating surface on the sleeve. One of these mating surfaces projects inwardly toward the axis to permit a small amount of movement of this mating surface in the direction of the axis. A process is also disclosed whereby the metallic sealing ring is cooled below its transition temperature to convert it to a martensitic state only during installation.

United States Patent. [191 Levinsohn et al.

[ 1 Sept. 18, 1973 [75] Inventors: Richard Levin sohn; James E. Jervis,

both of Menlo Park, Calif.

[73] Assignee: Raychem Corporation, Menlo Park,

Calif.

[22] Filed: Sept. 8, 1970 [21] Appl. No.: 70,321

[56] I References Cited UNITED STATES PATENTS Gredell 285/331 2,641,3816/1953 Bertrand.... 285/422X 3,279,806 10/1966 Bialkowski. 285/1 1 l -X2,002,086 5/1935 Dylewsk|.... 285/111 X 3,273,918 9/1966 Legarta eta285/112 X Primary Examiner-Andrew V. Kundrat Att0mey-Lyon & Lyon [57]ABSTRACT A hydraulic coupling is disclosed for connecting a hydraulicline to a hydraulic component such as a pump, compressor, cylinder orthe like. The coupling consists of an adapter which fits into an openingin the hydraulic component. In order to form a leak-free joint betweenthe adapter and the hydraulic component, a heat recoverable metallicsealing ring is placed between the surfaces. A heat recoverable sleeveis affixed to the hydraulic line and this sleeve mates with the adapterto form aseal. This seal results from the contact of a mating surface onthe adapter and a corresponding mating surface on the sleeve. One ofthese mating surfaces projects inwardly toward the axis to permit asmall amount of movement of this mating surface in the direction of theaxis. A process is also disclosed whereby the metallic sealing ring iscooled below its transition temperature to convert it to a martensiticstate only during installation.

13 Claims, 7 Drawing Figures HYDRAULIC COUPLING WITII METALLIC SEALINGMEMBER BACKGROUND OF THE INVENTION This invention relates to couplingswhich permit the connection of a hydraulic line to a hydraulic componentto form a leak-free seal. The hydraulic component may be a pump,compressor, hydraulic cylinder, or the like. More particularly, thishydraulic coupling is of the type which need not utilize any rubber orplastic parts, thereby permitting operation over a wide temperaturerange.

Many hydraulic components are provided with a standard threaded femaleboss. Most connectors utilize some adapter which screws into thethreaded boss. It is necessary that a fluid-tight connection be madebetween the hydraulic component and this adapter. A common prior artsealing method utilizes a rubber O- ring. It then becomes necessary toseal this adapter, which is often a threaded nipple, to the hydraulicline.

A common method for connecting a hydraulic line to a nipple extendingfrom a hydraulic component is to utilize flared tubing which istightened onto the threaded nipple by a nut which fits over the tubing.This nut holds the flared end against the threaded nipple. Anothercommon method is to place an elastic ring around the outside diameter ofthe tubing near its end.

This elastic ring is then caused to press against the outside of thetubing and the nipple by an overlying nut which screws into the threadednipple extending from the hydraulic component.

A metal to metal seal is disclosed in U.S. Pat. No. 3,083,989 issued toID. Press. In this coupling, a metal flange is tightened against amating surface. This system requires an elaborate arrangement to securethe flange-containing member to the hydraulic tubing.

More recently, heat recoverable metals have been utilized to form ametal to metal coupling. One such coupling is disclosed in U.S.application, Ser. No. 51,809 filed July 2, 1970, which was acontinuationinpart of Ser. No. 852,722. This application was filed by J.D. Harrison and J.E. Jervis and assigned to the assignee of the presentinvention, and the disclosure of this application is incorporated byreference herein.

Heat recoverable alloys are disclosed in U.S. application, Ser. No. 52,112, filed July 2, 1970. This application was filed by J .D. Harrison, J.Y. Choi and PR. Marchant and assigned to the assignee of the presentinvention, and the disclosure of this application is incorporated byreference herein.

SUMMARY OF THE INVENTION The coupling of this invention uses a newsystem for sealingan adapter to a hydraulic component and also uses anew system for sealing the adapter to a hydraulic line. It has long beenrecognized that a metal seal for hydraulic parts would have manyadvantages over a rubber or plastic seal. A metal seal is far lessaffected by temperature and cannot be softened or swollen by hydraulicfluids. Unfortunately, seals made from many metals tend to scratch orcause galling of the sealing surfaces of the hydraulic component.Toattempt to correct this problem, seals have been made of soft metalsbut then they lack the physical properties of the harder metals whichare necessary to withstand high pressure.

According to the present invention the seal between the hydrauliccomponent and the adapter comprises a metal seal of great strength butyet one which will not scratch or gall the sealing surface of thehydraulic component during installation. This beneficial combination ofproperties is permitted by the use of a metal which can exhibit vastlydifferent physical properties at different temperatures. As disclosed inthe aforementioned application Ser. No. 52,1 12 filed by Harrison, Choiand Marchant filed July 2, 1970, and in Chapter 22 of IntermetallicCompounds edited by J .H. Westbrook, Wiley & Sons 1967, certain alloyscan be made to convert from a relatively strong austenitic state to arelatively weak martensitic state by reducing the temperature of thealloy to below its transition temperature.

Alloys containing major proportions of titanium and nickel exhibit theability to be transformed reversibly from an austenitic state to amartensitic state by a temperature change. Small amounts of metals suchas iron, aluminum or manganese may be incorporated with major amounts oftitanium and nickel to result in an alloy with the desired transitiontemperature. By way of example, the following alloys (in atomicpercents) have transition temperatures above 1 96 C and below -75Titanium 50 Titanium 49 Titanium 50 Nickel 47 Nickel 50 Nickel 48 iron 3Aluminum l Manganese 2 a martensitic state by immersing it in readilyavailable liquid nitrogen.

The phase change from martensitic to austenitic can also be made toresult in heat recoverability by the addition of stresses to the alloy,particularly when it is in its martensitic state. This is described inthe aforementioned application Ser. No. 51,809 to Harrison and Jervisfiled July 2, 1970. Other heat recoverable metals are disclosed in U.S.Pat. Nos. 3,012,882 and 3,174,851 and Belgian Pat. No. 703,649 thedisclosure of which are incorporated by reference herein.

Thus, to form a strong, galling resistant seal, the adapter and metalseal are cooled to below the transi tion temperature of the seal and theadapter is affixed to the hydraulic component. The seal is then allowedto warm above its transition temperature at which time it converts fromits weak martensitic state to its strong austenitic state. The alloyfrom which the seal is made should have a transition temperature belowthe operating temperature of the hydraulic equipment in order to keepthe seal in its austenitic state during operation. This heatrecoverability may also be utilized to cause a change in shape of theseal as it is warmed above its transition temperature. Thus the seal, inits martensitic state, may be deformed so as to fit over an enlargedarea on the adapter and when warmed to its austenitic state will revertto its original configuration become captive. Additionally, the seal maybecome captive by engagement along its outer surface,

The second sealing point of the present invention exists between theadapter and the hydraulic line. This second seal also utilizes a heatrecoverable metal but for a different reason. A heat recoverable sleeveis first afi'ixed to the hydraulic line. This may be done by severalmethods including shrinking the sleeve over the hydraulic line in amanner described in the aforementioned application Ser. No. 51,809 Thissleeve is provided with a circular mating surface corresponding to amating surface on the adapter. Either one or both of these matingsurfaces is undercut to permit some movement of this mating surfacealong the direction of the axis of the coupling. Means are provided totighten and hold the sleeve against the adapter.

The resulting coupling is a removable all-metal coupling useful over awide temperature range and unaffected by solvatiog properties of thehydraulic fluid. Also, the hydraulic component is not scratched by theinstallation of the adapter and yet a seal of great strength results.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view partly insection of a preferred coupling according to the present invention.

FIG. 2 is an enlarged fragmentary view of the heat recoverable seal endportion of FIG. 1 shown prior to final engagement.

FIG. 3 is an enlarged fragmentary view of the heat recoverable seal endportion of FIG. 1 shown after final engagement.

FIG. 4 is an enlarged fragmentary view of the heat recoverable sleeveend portion of FIG. 1 shown prior to final engagement.

FIG. 5 is an enlarged fragmentary view of the heat recoverable sleeveend portion of FIG. 1 shown after final engagement.

FIG. 6 is an enlarged cross sectional view of an alternativelyconfigured heat recoverable seal end portion prior to heat recovery.

FIG. 7 is an enlarged cross sectional view of the heat recoverable sealend portion of FIG. 6 after heat recovery.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIG. 1, athreaded hole or boss is provided in hydraulic component 1 which isprovided with a mating surface 2 at the outer edge of the hole. Anadapter 3 is shown screwed into the boss in hydraulic component 1. Aheat recoverable V-ring seal 4 is shown in a recess of adapter 3 andmates both with the adapter and mating surface 2 thereby preventingfluid leakage between the hydraulic component and the adapter. Theadapter is threaded at one end to fit the threaded hole in the hydrauliccomponent. The outside diameter of the adapter is also threaded at itsother end to permit the attachment of coupling nut 5 thereon. Theadapter 3 has an intermediate hexagonal wrench flat which facilitatestightening of the adapter into the threaded hole. The recess is locatedbeneath this wrench fiat. Adapter 3 has an outer circular projectingring 6 which serves to protect circular mating surface 7. Recessed area8 has been formed behind circular mating surface 7 to permit somemovement of the mating surface as described below. This movementprovides an initial sealing pressure.

Heat recoverable sleeve 10 has been securely shrunk about hydraulic line1 l by the manner described in application, Ser. No. 51,809 to Harrisonand Jervis described above. Heat recoverable sleeve 10 has a projectingring 12 which provides scuff protection for the circular mating surface13 on the heat recoverable sleeve and also helps to align the adapterwith the sleeve prior to tightening. The sleeve 10 also has a recessedportion 14 which provides a stop for outer circular projecting ring 6 ofthe adapter. The shoulder 15 of coupling nut 5 pushes against theshoulder 16 of the heat recoverable sleeve 10 to cause the sleeve to bebrought against the adapter 3 when the coupling nut is screwed on theadapter. The operation of the seal between mating surfaces 7 and 13 ismore clearly shown in FIGS. 4 and 5 where adapter 3 and sleeve 10 areshown prior to tightening in FIG. 4 and after tightening in FIG. 5. Thecircular mating surface 7 of the adapter contacts mating surface 13 ofthe sleeve before outer circular projecting ring 6 of the adapter hastouched the recessed portion 14 of the sleeve 10. As the sleeve 10 isforced toward adapter 3 by coupling nut 5, the mating surface 7 of theadapter moves toward the hydraulic component in a direction generallyparallel to the axis of the coupling. This results from the provision ofrecessed area 8 which forms an inwardly extending arm 9 between thecircular mating surface 7 and the main body of the adapter. The resultis an action like a belleville spring which maintains a steady forcebetween mating surfaces 7 and 13 thereby forming an excellent seal. Thepressure of the hydraulic fluid on the recessed area 8 supplements thisforce and forms a dynamic seal between these mating surfaces.

Turning now to FIGS. 2 and 3, heat recoverable V- ring seal 4 is shownin enlarged cross section in a recessed portion of adapter 3. In FIG. 2,the seal is shown prior to tightening and in FIG. 3 after tightening. Abead 20 having a generally semi-circular outer surface is provided atthe end of one side of the V-ring which contacts mating surface 2 of thehydraulic component. An arcuate surface 21 is provided at the end of theouter side of heat recoverable seal 4 which contacts adapter 3. Theshape of seal 4 is such that hydraulic pressure within the couplingtends to expand the seal against the hydraulic component and the adapterat points 20 and 21. If desired a bead or arcuate surface may beprovided on each of the sides of the sealing ring thus preventing anyaccidental reverse positioning of the ring.

Turning now to FIGS. 6 and 7, there is shown an alternativeconfiguration of the heat recoverable seal.

In FIG. 7, heat recoverable seal 25 is shown in its sealing positionhaving mating areas at 26 and 27. The hydraulic pressure tends toincrease the seal at these areas. Since, in this configuration, the sealhas a mating area 27 on an outer surface of the adapter 3 it is lessdependent upon the position of the tightening surface which is shown InFIGS. 6 and 7 as tightening nut 28. Thus a fluid tight seal results eventhough the tightening surface is not threaded fully against thehydraulic component.

The seal 25 is shown in FIG. 6 in its martensitic state having beendeformed which enables it to be placed over the threads of the adapter3. When the seal is warmed above its transition temperature, it revertsto its stronger austenitic state and to its original undeformedconfiguration as shown in FIG. 7. This has the further advantage ofcapturing the seal. In order to hold tightening nut 28 in place, a locknut 29 is also threaded over adapter 3.

The heat recoverable alloy chosen for the seal should have a transitiontemperature such that it exists in its strong austenitic state at theoperating temperatures of the hydraulic system in which it is used. Thisheat recoverable seal should also be capable of being cooled to belowits transition temperature for installation of the adapter into thehydraulic component. In this way, damage to the mating surface of theboss can be minimized. As described in aforementioned application toHarrison and Jervis, Ser. No. 51,809 this may be a very low temperaturein that the adapter may be cooled in a fluid such as liquid nitrogenjust prior to connection with the hydraulic component. It is notnecessary that the V-ring seal be lowered in temperature below itstransition temperature if galling is not a problem.

The sleeve is normally connected to the adapter after the adapter hasbeen connected to the hydraulic component. The means for holding thesleeve against the adapter need not utilize a coupling hut but insteadcould use a circumferential clamp, a threaded union, or the like. Theprojecting ring on the adapter and that on the sleeve are not essentialto the operation of the coupling but are advantageous to prevent themating surfaces from becoming marred or scuffed. While the recessed areaand inwardly extending arm are shown in the drawings as a portion of theadapter, it could equally well be provided in that heat recoverablesleeve. It is only necessary that a belleville spring type of actionexist between the mating surface of the adapter and that of the sleeve.It is not necessary that the heat recoverable sleeve be fabricated fromthe same alloy as the heat recoverable seal. Its transition temperature,however, should be such that it also exists in its stronger austeniticstate at the temperatures at which it will operate.

The particular curvature of the heat recoverable seal shown in thedrawing may be varied to a more U shape or a more V shaped configurationas long as the fluid pressure will tend to expand the seal against itstwo mating surfaces. The hydraulic component need not be a piece ofequipment having a threaded hole but could be a second section ofhydraulic tubing thus constituting a union between hydraulic lines.While certain embodiments of the'invention are described, the inventionmay be embodied in other specific forms not departing from the spirit orcentral characteristic thereof. The present embodiments are therefore tobe considered in all respects as illustrative and not restrictive.

What is claimed is:

l. A coupling for connecting a hydraulic tubing to a hydraulic componentcomprising: i

an adapter capable of being attached to said hydraulic component at itsfirst end and having a sealing surface on its other end;

.a seal adapter to fit between said component and said adapter, saidseal being made from a metal capable of being converted to a martensiticstate at a temperature below the operating temperature of said couplingand existing in its austenitic state when at the operating temperatureof said coupling;

' means for attaching said adapter to said component;

a sleeve attached to said hydraulic tubing, said sleeve having a sealingsurface adapted to mate with the sealing surface of said adapter; and

means for holding said sleeve against said adapter to create asealbetween said sealing surfaces.

2; The coupling of claim 1, wherein said meansfor attaching the adapterto the coupling comprises a threaded hole in said component and acorresponding threaded nipple in said adapter.

3. The coupling in claim 1, wherein said means for holding said sleeveagainst said adapter comprises an enlarged end portion on said sleeve, acoupling nut capable of fitting over the body of said-sleeve, said nuthaving a threaded portion extending beyond said enlarged end portion anda corresponding threaded portion on said adapter.

4. The coupling of claim 1, wherein said seal is fabricated from analloy containing major proportions of titanium and nickel.

5. The coupling of claim 4 wherein said alloy further contains a minorproportion of a metal selected from a group consisting of iron,aluminum, and manganese.

6. The coupling of claim 1 wherein said sleeve is heat recoverable andis fabricated from an alloy containing major proportions of titanium andnickel.

7. The coupling of claim 6 wherein said alloy contains a minorproportion of a metal selected from a group consisting of iron, aluminumand manganese.

8. The coupling of claim 1 wherein said seal is a V- ring and has atleast one semi-circular sealing surface.

9. The coupling of claim 8 wherein said V-ring is symmetrical.

. 10. The coupling of claim 1 wherein said sealing surface of theadapter is borne by an arm extending radially inwardly from theperiphery of an inner surface of said adapter adjacent one end thereoftoward the longitudinal axis of said adapter and is hence capable ofaxial deflection with said arm upon connection of the adapter to saidsleeve.

11. The coupling of claim 10 wherein the sealing surface of said adapteris provided with an outer circular projecting ring and wherein said heatrecoverable sleeve is provided with a corresponding recessed portion topermit the contact of the sealing surface of said adapter with thesealing surface of said sleeve.

12. The coupling of claim ll wherein said sleeve is provided with acircular projecting ring located between the sealing surface and arecessed portion of the sleeve and wherein said adapter is provided witha corresponding recessed portion adapted to receive said ring.

13. In an adapter suitable for connection of a hydraulic component to ahydraulic line, said adapter having an elongate body hollowed about alongitudinal axis thereof for the passage of fluid therealong, theimprovement which comprises:

an arm extending radially inwardly from the periphery of an innersurface of said body adjacent one end thereof toward said longitudinalaxis, an axial projection on said arm extending toward said end andterminating in a circular radial sealing surface of diameter less thanthe diameter of said periphery, said projection being capable of axialdeflection with said arm upon connection of the adapter to said line;and ring integrally formed on said end of the adapter concentric aboutbut of diameter greater than said circular radial sealing surface, andprojecting axially outwardly beyond said sealing surface to define anannular space bounded by said ring, arm and projection and adapted toreceive a sealing surface carried by said line.

1. A coupling for connecting a hydraulic tubing to a hydraulic component comprising: an adapter capable of being attached to said hydraulic component at its first end and having a sealing surface on its other end; a seal adapter to fit between said component and said adapter, said seal being made from a metal capable of being converted to a martensitic state at a temperature below the operating temperature of said coupling and existing in its austenitic state when at the operating temperature of said coupling; means for attaching said adapter to said component; a sleeve attached to said hydraulic tubing, said sleeve having a sealing surface adapted to mate with the sealing surface of said adapter; and means for holding said sleeve against said adapter to create a seal between said sealing surfaces.
 2. The coupling of claim 1, wherein said means for attaching the adapter to the coupling comprises a threaded hole in said component and a corresponding threaded nipple in said adapter.
 3. The coupling in claim 1, wherein said means for holding said sleeve against said adapter comprises an enlarged end portion on said sleeve, a coupling nut capable of fitting over the body of said sleeve, said nut having a threaded portion extending beyond said enlarged end portion and a corresponding threaded portion on said adapter.
 4. The coupling of claim 1, wherein said seal is fabricated from an alloy containing major proportions of titanium and nickel.
 5. The coupling of claim 4 wherein said alloy further contains a minor proportion of a metal selected from a group consisting of iron, aluminum, and manganese.
 6. The coupling of claim 1 wherein said sleeve is heat recoverable and is fabricated from an alloy containing major proportions of titanium and nickel.
 7. The coupling of claim 6 wherein said alloy contains a minor proportion of a metal selected from a group consisting of iron, aluminum and manganese.
 8. The coupling of claim 1 wherein said seal is a V-ring and has at least one semi-circular sealing surface.
 9. The coupling of claim 8 wherein said V-ring is symmetrical.
 10. The coupling of claim 1 wherein said sealing surface of the adapter is borne by an arm extending radially inwardly from the periphery of an inner surface of said adapter adjacent one end thereof toward the longitudinal axis of said adapter and is hence capable of axial deflection with said arm upon connection of the adapter to said sleeve.
 11. The coupling of claim 10 wherein the sealing surface of said adapter is provided with an outer circular projecting ring and wherein said heat recoverable sleeve is provided with a corresponding recessed portion to permit the contact of the sealing surface of said adapter with the sealing surface of said sleeve.
 12. The coupling of claim 1 wherein said sleeve is provided with a circular projecting ring located between the sealing surface and a recessed portion of the sleeve and wherein said adapter is provided with a corresponding recessed portion adapted to receive said ring.
 13. In an adapter suitable for connection of a hydraulic component to a hydraulic line, said adapter having an elongate body hollowed about a longitudinal axis thereof for the passage of fluid therealong, the improvement which comprises: an arm extending radially inwardly from the periphery of an inner surface of said body adjacent one end thereof toward said longitudinal axis, an axial projection on said arm extending toward said end and terminating in a circular radial sealing surface of diameter less than the diameter of said periphery, said projection being capable of axial deflection with said arm upon connection of the adapter to said line; and a ring integrally formed on said end of the adapter concentric about but of diameter greater than said circular radial sealing surface, and projecting axially outwardly beyond said sealing surface to define an annular space bounded by said ring, arm and projection and adapted to receive a sealing surface carried by said line. 